1. Field of the Invention
The present invention relates to a method for trimming a resin film in which lugs which are generated at the time of forming the resin film by extruding and laminating resin to a surface of a substrate using a T-die.
2. Description of the Related Art
Conventionally, for example, at the time of manufacturing a laminated sheet which forms a resin film on a surface of a metal sheet, to dispose both end portions of the resin film which are made thick due to a neck-in phenomenon, following methods have been adopted. In one method, both end portions of the resin film are formed as lug portions at both sides of the laminated sheet and thereafter they have been trimmed together with a necessary minimum amount of the metal sheet. In the other method, the width of the metal substrate is sufficiently widened to prevent the generation of lug portions, the resin film is laminated to the metals sheet and thereafter both end portions of the resin film are trimmed together with the substrate of a corresponding quantity of width.
However, in the former method, there has been a problem that the fall of the lug portion or the entanglement or the adhesion of the lug portion to the substrate occurs along a path leading to a trimming step, while in the latter method, the portion of the laminated plate where the resin film is thick cannot be used and hence, there has been a problem that the use efficiency of the metal sheet is worsened. Further, in both methods, the trimmed resin film is integrally formed with the metal sheet and hence, there has been a problem that the trimmed resin film cannot be recycled.
Accordingly, the present invention has been made in view of such problems and it is an object of the present invention to provide a method for trimming a resin film which can recycle lug portions of a resin film after trimming, can easily trim the resin film even when the resin film is made of resin which becomes fragile when cooled, and can enhance the use efficiency of a laminated sheet by making resin coated portions disposed at both sides of the laminated sheet thin.
A method for trimming a resin film according to the present invention is characterized in that, at the time of coating molten resin at least on one surface of a substrate to form a resin film after allowing the substrate and the molten resin to pass through a nip portion between coating rolls, lug portions of the resin film are trimmed before the lug portions are cooled.
In this method, to perform the trimming easily and surely, it is preferable that the resin film is polyester resin and the trimming is performed in the state that a temperature of the lug portions of the resin film is set to not less than (Tgxe2x88x9220xc2x0 C.).
Further, by setting the relationship between a width (K) of substrate and a width (L) of a resilient body to (K) less than (L) and by performing the trimming of the lug portions by a nip pressure due to the resilient force of the coating rolls and edge portions of the substrate, it becomes possible to remove the resin-made lugs continuously and in a stable manner in the very vicinity of the end portions of the substrate without using knives or rotary cutters which may interfere with the substrate.
Further, in view of preventing the above-mentioned interference between the knives or the rotary cutters with the substrate in the above manner, it is desirable to set the relationship between the width (K) of substrate and the width (L) of the resilient body to (K) greater than (L) and to perform the trimming of the lug portions by a nip pressure due to a resilient force of guide belts and edge portions of the substrate.
In such a method, to surely discharge the lug portions to the outside, it is more preferable to perform the trimming by applying a removing force to the lug portions of the resin film.
Also in such a method, it is desirable to apply a removing force by setting the relationship between a travelling speed V1 of the substrate and a peripheral speed V2 of a guide belt such that they are not made equal. It is because that the trimming can be surely and easily performed.
It is further desirable to set the relationship between the travelling speed V1 of the substrate and a speed V3 of a discharge belt to V1 less than V3. It is because that a removing force can be applied by using the discharge belt.
In the same manner, to apply a removing force, it is further desirable to set the relationship between the travelling speed V1 of the substrate and a speed V4 of the lug portions of the resin film to V1 less than V4.